1. Field of the Invention
The present invention relates to a disk drive (for example, a magnetic disk drive) that uses a head to write data at any position on a magnetic disk or any other type of disk or read data written at any position thereon. More particularly, the present invention is concerned with a disk drive having the capability to shorten a startup time of equipment connected to a main disk drive unit, and the capability to improve the reliability of data, of which the use frequency is high, at the time of startup of the equipment. Moreover, the present invention is concerned with a control method, for a disk drive, controlling the disk drive after the power supply of the disk drive is turned on or during writing or reading of data.
2. Description of the Related Art
Conventionally, first, after the power supply of a disk drive such as a magnetic disk drive is turned on, the disk drive is controlled in a mode in which, after a setup, including determination of the initial conditions for the disk drive and start of a spindle motor, is completed, the busy state of a disk is canceled so that the disk drive will enter a command receivable state in which the disk drive can receive a command from an external host processor or the like.
Secondly, when a power-up-in-standby capability is used to cancel the busy state without start of the spindle motor, the disk drive is controlled in a mode in which on receipt of a Read command or any other command requiring access to a storage medium such as a disk, the spindle motor is started and the storage medium is accessed.
For an easy understanding of problems underlying a conventional control method of controlling a disk drive after the power supply of the disk drive is turned on or during writing or reading of data, the conventional control method for a disk drive will be described in conjunction with FIG. 1 to FIG. 3 that will be mentioned later in “Brief Description of the Drawings.”
FIG. 1 illustrates a flowchart describing a first example of the conventional control method for a disk drive relevant to the first control mode. FIG. 2 illustrates a flowchart describing a second example of the conventional control method for a disk drive relevant to the second control mode. FIG. 3 illustrates a flowchart describing a third example of the conventional control method for a disk drive relevant to the second control mode.
Referring to the flowcharts of FIG. 1 to FIG. 3, the first to third examples of the conventional control method for a disk drive will be described below.
As apparent from the flowchart of FIG. 1, when the power supply of a disk drive is turned on at step 400, the initial conditions for the disk drive are determined at step 401. The determination of the initial conditions includes self-diagnosis of hardware of the disk drive and determination of settings thereof, and determination of settings of firmware (or software) installed in the disk drive. Furthermore, after the start of the spindle motor (may be abbreviated to SPM) is completed at step 402, the rotation of the spindle motor becomes steady-state. Thereafter, drive-specific information representing the attributes of the disk drive is read at step 403. Thereafter, the busy state of the disk drive is canceled at step 404, and a command reception wait state (command receivable state) is established at step 405. In this case, an external host processor or the like cannot issue a command until the busy state is canceled.
The flowchart of FIG. 2 describes an example of a control method for a disk drive to be applied in a case in which the spindle motor is not started but a power-up-in-standby capability is used to cancel a busy state. Herein, the power supply of the disk drive is turned on at step 410, and the initial conditions for the disk drive are determined at step 411. Thereafter, at step 412, the busy state of the disk drive is canceled but the spindle motor is not started. The command reception wait state (command receivable state) is established at step 413. Even in this state, the external host processor or the like cannot issue a command until the busy state is canceled.
Furthermore, an interrupt to be performed when a command is received from an external host processor or the like will be described in conjunction with the flowchart of FIG. 3. At steps 420 and 421 in the flowchart of FIG. 3, a Read command or any other medium access request command that requires access to a storage medium (for example, a disk) is received. If the storage medium is verified to be accessible (step 422), a command executor executes the command (step 425). If the storage medium is verified to be inaccessible because the spindle motor is not started, the spindle motor is started at step 423 in order to access the storage medium. Thereafter, after the start of the spindle motor is completed, the rotation thereof becomes steady-state. Thereafter, drive-specific information representing the attributes of the disk drive is read at step 424.
By the way, information important for activating equipment (for example, a host system such as a host processor) connected to the main disk drive unit is often written in a sector near a sector located at the leading position on a disk. Therefore, immediately after the power supply of the disk drive is turned on and the busy state thereof is canceled, a Read command is often issued in order to read the sector near the sector located at the leading position on the disk.
In general, storage media including a disk comprise a plurality of concentric tracks that can be accessed by a head. Each track is segmented into a plurality of regions. Each of the regions is called a “sector.”
According to the conventional control method for a disk drive described in conjunction with FIG. 1 to FIG. 3, problems (1) to (4) described below take place.
(1) Immediately after the power supply of the disk drive is turned on, the busy state of the disk drive is not canceled until setup including start of the spindle motor is fully completed. Therefore, equipment connected to the main disk drive unit cannot issue a command as long as the magnetic disk drive is busy. A command instructing startup of equipment connected to the main disk drive unit cannot be issued until the busy state of a disk is canceled.
(2) When the power-up-in-standby capability is utilized, as the spindle motor is not started, the time from the instant the power supply is turned on to the instant the busy state is canceled is shortened. In this case, a command other than a medium access request command is handled immediately. However, when a Read command or any other medium access request command is issued, after the spindle motor is started, a storage medium cannot be accessed until the rotation of the spindle motor becomes steady-state. Therefore, a command handling time at which a medium access request command is handled is delayed.
(3) The time from the instant the power supply of the disk drive is turned on to the instant the busy state thereof is canceled, and a delay in a command handling time occurring after the busy state is canceled are reflected on the startup time of equipment connected to the main disk drive unit.
(4) Furthermore, information important for starting up equipment connected to the main disk drive unit is often written in an area starting with a sector located at the leading position on a disk in the disk drive and including several sectors. If the information cannot be read, equipment connected to the main magnetic disk drive may not be started up.
For reference, Patent Documents 1 to 4 relating to the conventional control method for a disk drive are listed below. The arts disclosed in the Patent Documents 1 to 4 share the same problems as the aforesaid ones underlying the conventional control method for a disk drive.
1. Patent Document 1: Japanese Unexamined Patent Publication (Kokai) No. 7-271518
2. Patent Document 2: Japanese Unexamined Patent Publication (Kokai) No. 9-54742
3. Patent Document 3: Japanese Unexamined Patent Publication (Kokai) No. 63-53753
4. Patent Document 4: Japanese Unexamined Patent Publication (Kokai) No. 7-192380